Eragrostis variabilis
Poaceae or Grass family [Five-minute families]
Synonyms: Eragrostis equitans, Eragrostis hawaiiensis, Eragrostis hobdyi, Eragrostis niihauensis, Eragrostis phleoides, Eragrostis thyrsoidea, Eragrostis variabilis var. ciliata, Eragrostis wahowensis, Poa variabilis
Kāwelu
ʻEmoloa, Kalamālō
Lovegrass, Variable lovegrass
Natural Range & Environment
Eragrostis variabilis is endemic to Kure Atoll (Mokupāpapa), Midway Atoll (Pihemanu), Pearl and Hermes Reef (Holoikauaua), Lisianski Island (Papaʻāpoho), Laysan Island (Kauō), and Nīhoa Island, as well as all the main Hawaiian Islands. It is found on dunes, in grasslands, open sites in dry forest, and exposed slopes, ridges or cliffs [Wagner et al. 1990].
Kāwelu is often the dominant plant in native Hawaiian seabird habitat. For example, the majority of Christmas shearwaters (Puffinus nativitatis) that breed on Nīhoa nest in the tufts of kāwelu or ʻakoko (Chamaesyce celastroides) thickets [Evenhuis & Eldredge 2004].
On Midway Atoll, this kāwelu shelters a Laysan albatross chick from the sun. Wild kāwelu growing on a barren rockface in Eastern O‘ahu. Young green panicle (branched inflorescence). Mature tan panicle (photograph courtesy of Taylor Justason CC BY-NC 4.0). A roadside trial on O‘ahu using kāwelu. A Kaho‘olawe "restoration box" using kāwelu, pili, ʻaʻaliʻi and ʻāweoweo. (Midway Atoll and Kaho‘olawe photographs, including header, courtesy of Forest & Kim Starr CC BY 3.0 US).
Description
Eragrostis variabilis is a perennial bunchgrass about two feet (61 cm) tall when mature, with a lifespan often greater than five years. The pale to bluish-green leaves are about a centimeter (0.4 in) wide with a rough upper surface and a glabrous (hairless) lower surface. Most kāwelu we have seen have spike-shaped and dense panicles (branched inflorescence), but there are populations where the panicles are wider and more open. Each panicle has hundreds (we have never really counted them) of tiny perfect (bisexual) flowers. Each pollinated flower develops into an ovoid caryopsis (the fruit of plants in the Grass family, sometimes referred to as a "grain") that is tan to dark reddish brown when ripe, turning grayish with age. Kāwelu blooms repeatedly year-round when cultivated. Wild plants seem to have regular flowering periods, particularly those in very dry areas, which stop blooming during the hot and dry months.
Growth Requirements
General
Eragrostis variabilis (and bunchgrasses in general) is not a showstopper. However, it and other grasses and sedges add a new shape or form to a landscape, filling in any gaps, and fulfilling our natural desire to see more than just the showy flowers and broad leaves of dicots. Use kāwelu as an accent, groundcover, or planted en masse (about 3 feet (1 m) apart) for erosion control. It can also be kept as a container plant, but be mindful of its roots becoming potbound. Do this by gradually transferring it to larger and larger pots. Then, when full size (or the size you desire), occasionally remove it from its pot, reduce the root mass (i.e., prune its roots), prune down all or remove some of its leaves, and repot. Water heavily and let the plant recover.
Kāwelu does best in a site with full sunlight for all or most of the day. It looks best in windy locations where its leaves will sway back and forth (see Uses below). Water regularly for the first two or three weeks after planting to allow time for root establishment. Then, slowly reduce your watering to once or twice a month in hot dry sites — less or no watering in places with more rainfall. In general, kāwelu does best in soil (or media) that is surface dry but moist a few inches down. Avoid overwatering because waterlogged or constantly wet soil (or media) can cause problems (e.g., root rot).
Kāwelu is tolerant to drought, extreme heat, strong winds, and salt spray (with some burning if too close to the ocean). It is not picky about soil type and will grow in lava/cinder, sandy, coralline, clay, and organic-dominant soils, provided the soil drains water well.
Eragrostis variabilis grows fairly quickly, reaching a mature size of about two feet (61 cm) tall in one to two years. At about this size (age), it will also start producing flower spikes. To keep your plant looking its best, apply a small amount of a balanced slow-release fertilizer with minor elements every six months to a year, or occasionally spray your kāwelu with an organic or inorganic water-soluble fertilizer diluted to ⅓ to ½ its recommended strength. Do not over-fertilize to avoid potential pest problems. Depending on your aesthetic, remove or keep any old seed stalks. And, because kāwelu doesn't have a super-long lifespan in cultivation (usually more than five but less than ten years in our experience), collect and store away (in your refrigerator) some seeds to sprout for a replacement plant(s). There is some anecdotal evidence that regularly cutting off its flower spikes can prolong the lifespan of kāwelu.
Pests and Diseases
Over-fertilized kāwelu are more likely to be attacked by aphids, mealybugs, and scale insects, which are often farmed and protected by ants. Grasshoppers, snails, and slugs are attracted to and may chew on young plants or the new leaves of older plants. Refer to the Pests & Diseases page for ways to battle each of the above-mentioned pests.
Uses
Ancient Hawaiian
Kāwelu was occasionally substituted for pili (Heteropogon contortus) as thatching [Krauss 1993]. According to Neal [1965], kāwelu is a hula step that mimics the waving movement of this grass.
Modern
Eragrostis varabilis is used extensively to restore native Hawaiian seabird habitat, particularly in the Northwestern Hawaiian Islands, as well as for erosion control in places like Kaho‘olawe [Starr].
Special Features and Information
General
The Grass family (Poaceae) is a diverse group of plants that includes approximately 12,000 species within 780 genera worldwide. It is the most economically important plant family, providing humans with food, building and landscape materials, and fuel [WikipediA;Poaceae].
In Hawai‘i, there are about 50 species of native grasses. Many of these are endemic, with several being rare or endangered. There are also many, many more alien and naturalized (i.e., growing and reproducing in the wild) species of grasses today in Hawai‘i [Flora of the Hawaiian Islands].
The lovegrasses (Eragrostis spp.) make up about 300 species in the Grass family worldwide. In Hawai‘i, there are currently (2025) nine recognized native species, of which eight are endemic. Of these, the Pacific lovegrass (Eragrostis deflexa) is considered rare, while Fosberg's lovegrass (E. fosbergii) and the Maui lovegrass (E. mauiensis) are considered extinct [Flora of the Hawaiian Islands].
Kāwelu is an important food source and nesting site for the Laysan finch (Telespiza cantans), a honeycreeper endemic to Laysan (Kauō), but also introduced to Midway Atoll and Pearl and Hermes Reef. These birds also once inhabited Oʻahu and Molokaʻi in prehistoric times [Pratt 2005].
Hawaiian Name
In addition to being the Hawaiian name for Eragrostis variabilis, kāwelu is the name for a hula step inspired by the movement of the grass, as well as a seaweed, possibly Wrangelia penicillata, which looks like a kāwelu panicle [Pukui & Elbert 1986]. In Hawaiian mythology, Kāwelu is the name of the wife of Hiku, who strangled herself because she believed she was unloved. Hiku then went to Milu, ruler of the underworld, to bring her back [Combined Hawaiian Dictionary 2020; under Milu].
Etymology
Eragrostis is derived from the Greek word eros, meaning "loving" (in an erotic sense), and Agrostis, the Latin name of a genus of fodder grasses [Wagner et al. 1990]. The species name, variabilis, is Latin for "variable, not constant" [Gledhill 2008], perhaps in reference to the variable form of the species panicles.
BPK